


Out of nowhere, it can feel like your four-month-old is struggling with sleep and keeping you up at night again. A pediatric sleep consultant shares how to survive the four-month sleep regression.
Many newborn babies sleep well, but those restful nights can go downhill when they get around four months. Parents can quickly go from having a baby that fell asleep quickly and only up once or twice a night to a baby that’s up every 60 minutes.

What is a sleep regression?
You may hear others talk about the 8-month, 12-month, or 18-month sleep regressions as a new parent. Sleep regressions are often caused by your baby going through a developmental milestone, like learning to crawl or walk or create simple sentences.
Sleep regressions are often caused by your baby going through a developmental milestone, like learning to crawl or walk or create simple sentences.
A regression, however, is defined as “a return to a former or less developed state.” Because your baby’s sleep is going through the exact opposite, parents should be talking about the “four-month sleep progression.”
How long does the four-month sleep regression last?
There are going to be setbacks in your baby’s sleep. Teething, sickness, and travel are a few that can do a number on rest a few nights in a row.
You can expect your baby’s sleep regression to last between one and six weeks. Remember that every baby (and sibling!) is different from the next.
Thankfully, I’m happy to share that once you’re out of the four-month sleep regression, it’s over (until the following regression, of course).

What causes the four-month sleep regression
Between the third and fourth months, a baby’s sleep reorganizes from two stages into four stages. As they start to spend more time in light sleep, your baby has more opportunity to come out of a sleep cycle, which typically lasts about 45 minutes.
If your baby depends on something external to get to sleep, like a feed, pacifier, or being rocked, they will need that same external help a lot more often during the night once the development of sleep occurs.
Everyone wakes or almost wakes in between sleep cycles. If your baby is depending on something external to get to sleep, like a feed, pacifier, or being rocked, they will need that same external help a lot more often during the night once the development of sleep occurs.
A four-month-old baby is in and out of four stages of sleep instead of two. With this change comes a fight-or-flight response, doses of adrenaline, and lots of crying.
Parents can find themselves in a pretty awful predicament with night wakings between every 45-minute sleep cycle. At least now you know why sleep regressions can occur, and it’s not that you’re a terrible parent or are doing something incorrectly.

How to survive the four-month sleep regression
Learning how to survive the four-month sleep regression is essential for your mental health. These four tips can help.
A quick glance:
- Keep the room as dark as possible
- Use plain white noise
- Know your baby’s appropriate wake windows
- Pause before tending (and set a timer)
Keep reading for more details on these tips and why they help navigate a sleep regression – at any age.
1. Keep the room as dark as possible
Science has proven that we all sleep best in the dark. You must do what you can to cover every inch of light coming through the bedroom window.
You can invest in customizable blackout blinds like Blackout EZ, cover the window with foil or cardboard, or purchase a portable blackout pod like the SlumberPod. You can save $20 using our exclusive SlumberPod link. Shop now.
2. Use plain white noise
White(or pink or brown) noise is a great addition when creating the perfect sleep environment. Loud white noise can trigger the calming reflex in newborns.
For infants, the white noise blocks out environmental noise that might prematurely jolt your baby out of a sleep cycle. You can easily control this mini sound machine from your phone without disrupting your baby.
Pro tip: It’s best to place the machine about 4-6 feet away from your baby and keep it on all night and during naptime. Volume-wise, it should be on a lower setting rather than high (you should be able to converse with it on).
3. Know your baby’s appropriate wake window
If you keep a baby up too long, they will become overtired. Overtiredness is one of the most common reasons for lots and lots of crying at bedtime or naptime.
Know how long your little one should be awake – also known as their wake window – depending on their age, and watch for sleepy cues. Knowing those cues and watching the clock will make a huge difference.
4. Pause before tending (and set a timer)
Becoming a great sleeper is a learned skill.
If you teach your baby how to fall asleep independently and get themselves back to sleep upon nighttime wakings, you must give them a chance to do just that.
Here’s what to do:
When you hear your little one start to protest, set a timer. Now, how much time is up to you. But if you don’t set a timer, 2 minutes will feel like 30, and you’ll run into your baby’s room before they have even had the opportunity to show you they can do it.
Just pause and take a breath.
By teaching your baby to fall asleep at night, prop-free, without feeding, a pacifier, or bouncing, you are giving them a lifelong skill that will benefit them.
And let’s not gloss over what parents gain from a well-rested baby. Sleep not only helps your health but can also positively impact your relationship with your partner.

A closer look at newborn sleep in general
Newborns only have two stages of sleep compared to the four stages that adults have: deep sleep or deeper sleep. This explains why they can sleep in a noisy room with tons of light, which doesn’t bother them.
Most newborn babies learn to fall asleep during a feed, with a pacifier, or rocked. This habit can significantly contribute to the 4-month regression when their sleep starts to develop.
If you can prevent your newborn from relying on the same external “sleep prop” every time they sleep, that can be helpful. Of course, there is a time and place for these soothing methods, which can help save your sanity.
Final thoughts on sleep regressions
Ultimately, remember that all babies are different; some will learn this whole sleep thing quite quickly, and some will be more resistant. Keep tuning into your baby’s needs as you navigate the four-month sleep regression.
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Andi helps tired parents find the best sleep training method for their baby to achieve a good night's rest. After struggling with her daughter's sleep, she was desperate for a solution to help them sleep better throughout the night. She's now a certified sleep consultant helping families rest better every night.